Recent developments in technology have emphasized the need for display devices in all aspects of everyday activities. Visual information is almost a human necessity enabling the individual and society to function at maximum efficiency.
Display devices can be divided into two classes. Emissive type displays, such as cathode ray tubes (CRT), electro luminescence (EL), light emitting diodes (LED), vacuum fluorescent display (VFD), field emission display (FED), plasma display panel (PDP), and similar displays are capable of displaying images without the aid of a lighting unit or a backlight unit due to their ability to spontaneously emit light. On the other hand, non-emissive type displays, such as liquid crystal displays (LCD), are incapable of displaying images on their own and therefore require the inclusion of a lighting unit or backlight unit as they are not capable of spontaneous emission of light.
One of the widely used and ubiquitous display devices is the LCD since it is inexpensive. Better LCD technologies such as In Plane Switching (IPS) have vastly improved the display quality of LCDs while maintaining lower power consumption and lower heat dissipation in comparison to similarly sized PDP or CRT displays.
With the increasing use of display devices in various fields, there is a constant push for LCD devices to have better color reproduction, high contrast ratios, and low power consumption. Even the form factor and other desired physical aspects of LCD devices, such as low weight, thinness, varying shapes and even flexibility have been dominant considerations in the market. In particular, certain applications require LCD devices to contain one or more holes to allow material or parts to go through the hole.
The presence of a hole in the LCD device creates a difference in the luminance values, or the luminous intensity per unit area of light, between the front of the hole and behind the hole in relation to the location of the light sources. As such, the light emitted by the backlight unit on the liquid crystal panel is uneven, resulting in lower image quality. Hence, there is a need to reduce this difference in luminance values in order to increase the image quality of the LCD device.